Founding Engineer, Agent Systems

C&D Talent Advisory; Cambridge; On-site; GBP 130,000 - 170,000; Full time

Benefits offered by this job

Roof terrace

On-site facilities

EMI-eligible equity

Daily team lunch

Specialty coffee

Job summary

TechTree is recruiting for a Founding Engineer, Agent Systems in London (King's Cross). This on-site, full-time role offers founding-level ownership of the agent platform and the chance to shape AI reliability for high-stakes production systems.

You'll own orchestration, multi-step workflows, sandboxing, and AI-quality infrastructure, building production-grade agent systems in a seed-stage, high-growth startup with seven-figure revenue from enterprise contracts.

Qualifications

• Strong professional backend engineering experience.
• 1–2+ years shipping production LLM-powered features.
• Strong TypeScript or Node.js experience.
• Experience building customer-facing production AI systems.
• Hands-on experience with agent frameworks.
• Experience with tool calling and multi-step orchestration.
• Production experience building AI evaluations.
• Experience with dataset curation and regression testing.
• Understanding of LLM-as-judge approaches and failure modes.

Responsibilities

• Build and evolve the core agent orchestration platform.
• Design multi-step agent workflows and tool-calling systems.
• Build context-management and agent-scaffolding infrastructure.
• Develop secure sandboxing for agent execution.
• Implement prompt-injection defenses and other agent-security controls.
• Build production evaluation frameworks for fuzzy, high-stakes outputs.
• Curate evaluation datasets and regression suites.
• Design and improve LLM-as-judge systems.
• Evaluate model performance across upgrades and provider changes.
• Build retries, fallbacks, and circuit-breaker mechanisms.
• Own prompt versioning and AI-quality infrastructure.
• Design systems around async processing, queues, and idempotency.
• Define the internal standard for production AI quality.
• Own AI reliability and make ship/no-ship decisions when necessary.

Skills

Backend engineering

LLM features

TypeScript

Node.js

Agent frameworks

Tool calling

AI evaluations

Asynchronous systems

Systems thinking

Ownership

Tools

Docker

Postgres

Terraform

GitHub Actions

Azure

Express

Claude Code

Job description

Hiring via TechTree

This is a role that TechTree is recruiting for on behalf of one of its clients.

TechTree is an AI-driven recruitment platform working with high-growth companies.

When you apply, TechTree's AI Agent matches you not just to this role but to other relevant opportunities across its network, so one application can unlock multiple roles.

Founding Engineer, Agent Systems | London

• Location: King's Cross, London
• Work model: On-site by default, with some flexibility
• Employment: Full-time
• Level: Mid-Senior / Founding Engineer
• Experience: Typically 6–7+ years, with flexibility for exceptional AI-native profiles
• Estimated compensation: £130,000–£170,000 + Equity
• Industry: Enterprise AI / Agent Systems
• Environment: Seed-stage, high-growth startup

About the opportunity

• Join a seed-stage company building AI-native risk infrastructure for regulated enterprises
• Work on production AI systems used across financial services, regulated technology, and healthcare
• Own the agent platform powering customer-facing AI features
• Build the orchestration, evaluation, and reliability layers around frontier LLMs
• Turn model capabilities into production systems that domain experts can trust
• Set engineering standards for when AI features are reliable enough to ship
• Operate with founding-team levels of ownership and technical influence
• Work in a company already generating seven-figure revenue through multi-year enterprise contracts

What you'll own

• Build and evolve the core agent orchestration platform
• Design multi-step agent workflows and tool-calling systems
• Build context-management and agent-scaffolding infrastructure
• Develop secure sandboxing for agent execution
• Implement prompt-injection defenses and other agent-security controls
• Build production evaluation frameworks for fuzzy, high-stakes outputs
• Curate evaluation datasets and regression suites
• Design and improve LLM-as-judge systems
• Evaluate model performance across upgrades and provider changes
• Build retries, fallbacks, and circuit-breaker mechanisms
• Own prompt versioning and AI-quality infrastructure
• Design systems around async processing, queues, and idempotency
• Define the internal standard for production AI quality
• Own AI reliability and make ship/no-ship decisions when necessary

What we're looking for

• Strong professional backend engineering experience
• 1–2+ years of experience shipping production LLM-powered features
• Strong TypeScript or Node.js experience
• Experience building customer-facing production AI systems
• Hands-on experience with agent frameworks
• Experience with tool calling and multi-step orchestration
• Production experience building AI evaluations
• Experience with dataset curation and regression testing
• Understanding of LLM-as-judge approaches and failure modes
• Strong systems-thinking ability
• Experience with asynchronous systems and queues
• Understanding of idempotency and reliability patterns
• Strong product-engineering mindset
• Ability to own features from customer problem through production deployment
• High level of autonomy and accountability
• Based in London or able to commute regularly for an on-site-first role

Particularly valuable experience

• Anthropic APIs
• OpenAI APIs
• Open-weight models
• Production LLM workloads at scale
• Agent orchestration frameworks
• AI evaluation infrastructure
• Model fallback architecture
• Prompt versioning
• Prompt-injection defense
• Agent security
• Sandboxed tool execution
• Production RAG systems
• High-stakes AI applications
• Compliance
• Governance, Risk and Compliance (GRC)
• Audit technology
• Cybersecurity
• Financial services
• Regulated enterprise software

Strong profile signals

• Former founder or technical founder
• Former CTO returning to hands‑on engineering
• Founding or early-stage engineering experience
• Experience at a high‑growth product company
• Experience at a leading technology or AI organization
• Significant independent AI projects or side projects
• Strong evidence of product ownership
• History of shipping customer‑facing systems end‑to‑end
• AI‑native development workflow
• Heavy use of coding agents such as Claude Code or equivalent
• Ability to move between product, backend, AI systems, and reliability work
• Strong technical judgment rather than purely research‑oriented expertise

This role may not be the right fit if you

• Have exclusively front‑end or front‑end‑first engineering experience
• Have a purely AI research background without production software engineering ownership
• Have worked primarily in Developer Relations or Developer Experience
• Have only built internal AI tools rather than customer‑facing production systems
• Lack meaningful backend engineering experience
• Have AI experience limited to prototypes or demos
• Prefer research over shipping production products
• Lack experience taking ownership of production reliability
• Prefer narrowly scoped engineering responsibilities
• Are uncomfortable making judgment calls around AI quality and production readiness
• Are not comfortable working primarily on‑site in London

Technical environment

• TypeScript
• Node.js
• React
• Tailwind
• Express
• Azure
• Postgres
• Terraform
• GitHub Actions
• Docker
• Anthropic‑first AI stack
• Claude Code

What you'll get

• Founding‑level ownership of the agent platform
• Significant influence over AI architecture and engineering standards
• Opportunity to build production‑grade agent systems from an early stage
• Direct impact on customer‑facing AI quality and reliability
• Exposure to frontier LLM APIs in demanding production environments
• Work on technically difficult evaluation and reliability problems
• Close collaboration with company leadership
• Top‑decile London market compensation
• Meaningful EMI‑eligible equity
• Significant AI tooling and API budgets
• Daily team lunch
• Specialty coffee
• King's Cross office with roof terrace and on‑site facilities
• Fast-moving engineering environment with high autonomy